Tracking MUNs to Limit Ammonia Emissions

Milk urea nitrogen (MUN) is an affective and easy tool for farmers to track how well their cows are utilizing nitrogen from the feed, but it can also be a tool to evaluate air quality on farms. 

Milk urea nitrogen on well managed farms ranges from 8 mg/dl up to 12 mg/dl.  Values higher than 12 indicates that there is nitrogen being wasted and the ration formulation needs to be evaluated.  There are two things that should be looked at in the ration when MUNs are running high.  The first is the amount of protein in the ration.  If the cow is fed more protein than she needs that protein will first be converted to ammonia in the rumen.  Ammonia is then absorbed into the blood stream where it is converted to urea due to the toxicity of ammonia to the cow.  Much of this urea is then excreted as a waste product in the urine, but some will also go into the milk.  Therefore, MUN is a good indicator of how much urea is excreted in the urine.  The other thing to look at in the ration is the amount of available energy.  If there isn't enough energy for the level of protein the protein will be broken down without subsequent microbial protein production and ammonia will be formed.

From a farmer perspective high MUNs indicate that money is being wasted on protein that is not being used for milk production.  From an environmental perspective urea that is excreted in the urine is quickly converted back to ammonia by the urease enzyme found in the feces.  This ammonia creates air quality concerns for the farm and the surrounding area.  It is estimated that 25% of the nitrogen that ends up in the Chesapeake Bay comes from the air as ammonia. 

Protein Utilization on Pasture

Although we tend to worry about cows getting too much protein from the pasture during the lush spring months, the fall bump can also lead to too much protein intake on pasture. Good quality pastures tend to provide more protein than energy in general, but during the spring and fall growing seasons that ratio tilts even further towards protein. Therefore, supplementing either grain, corn silage, or a total mixed ration (TMR) is usually necessary to improve production in grazing herds and increase the utilization of protein from the pasture.

The energy component of the diet can greatly influence how the protein from the pasture is digested. This is because when a cow eats she is not only eating to support her own needs, but also the needs of the microbes in her rumen. When there is energy and protein available at the same time these microbes break down the feed (energy and protein) and use the end products to produce more of themselves (microbial protein). They then pass out of the rumen serving as a protein source for the cow. However, if there isn’t enough energy available, as is the case on pasture, the protein in the pasture will still be broken down, but instead of being converted to microbial protein, feed protein is broken down to ammonia. Ammonia is absorbed into the blood where it is converted to urea. This urea in the blood is the source of milk urea nitrogen (MUN) and urea nitrogen in the urine. Since MUN is coming from the same blood urea nitrogen pool as urea in the urine it is a good indicator of urea excretion and utilization. Excessive urea production and excretion in urine can lead to water and air quality concerns.

Also, from the cow’s standpoint, the production and excretion of excess urea takes energy. There is a paper out of Penn State by Kolver and Muller that estimated excess urea excretion cost the cow almost 4 lbs of milk/day! This is because it takes energy for the cow to convert the absorbed ammonia, which came from excess protein supply in the rumen, to urea. Ammonia is toxic to the cow so this conversion to urea is a necessary energy utilizing process, which cannot be eliminated, but can be reduced through lower protein rations and appropriately matching ration protein and energy concentrations. Are you willing to leave 4 lbs of milk on the table knowing that not only did you lose milk production, but you also lost feed efficiency and it could have been prevented if MUN had been tracked and maintained within the recommended 8-12 mg/dl?

One way to improve nitrogen efficiency from the pasture and decrease MUN is to supplement the pasture with a partial TMR. A study from Penn State supplemented pasture with a partial TMR and saw an 8 lb/day increase in milk production and a 3 mg/dl decrease in MUN compared with pasture supplemented with 19 lb of concentrate. Supplementing with a grain mix or corn silage are also options, but a mixture is usually better at providing digestible energy that is not too fermentable in the rumen.

Although the pasture may be supplying a large portion of the dry matter, supplementing the pasture is necessary to maximize its full potential. Total mixed ration supplementation of pasture allows for better capture of protein from the pasture the nitrogen utilization will be increased, which can be tracked though MUN values. For all the effort that goes into developing and maintaining high quality pastures lets be sure we are getting all we can out of these efforts.

Getting a Farmer's Attention

Many nutrient management, water quality, and general environmentally minded folks get frustrated at times that farmers aren’t as engaged in these issues as they would like or don’t implement changes on the farm at the pace they would like.  Why is that?  Well, it boils down to what is your priority.  If you work in the environmental field and live and breathe water quality and air quality all day you begin to believe that it is the most important thing, which rightly you should.  If environmental quality is your field it makes sense that air and water quality are top priorities for you and you may tend to assume that they should be for others. 

Farmers, on the other hand, do care about water and air quality and other environmental concerns, but that is not their entire job so it is not their priority issue.  Farmers actually have very complicated jobs with a lot of things pulling them in many different directions.  Farmers are raising, large numbers of animals.  Even a 40-cow dairy, which is small in the dairy world, is a daunting task when you think about actually taking care of 40 animals plus the 20 calves and heifers that would also be on that farm.  I work in the dairy industry and I know I would be overwhelmed with all they have to deal with.  Cows get sick and need to be treated, maybe they need help calving, they need extra care and attention after calving even if everything went well, they need to be fed multiple times a day, they need to have access to water, they need to be milked at least twice a day, their housing and stalls need to be maintained daily so that they are comfortable, and the list could go on and on.

 Just dealing with the needs of the cows is a lot of work, but farmers also need to provide food for these animals, and in many cases that means growing the corn, soybeans, and hay that will be fed to the cows.  Good quality feed is necessary to have high levels of milk production, which is necessary for a farm to make money and continue in the business.  That means fields need to be planted and fertilized in a timely manner, hay needs to be chopped multiple times throughout the year and timed so that it has time to dry before getting rained on, and crops need to be harvested a precise times and stored properly  so that there is little loss of this precious feed through the year.

All of these animal care and feed production activities take a lot of time and deserve the attention of the farmer.  These are, and should be, their priorities if they want to remain in the dairy business.  Although many farmers do care a great deal about the environment it just doesn’t make it to the top of the priority list very often.  Therefore, for someone working in the environmental field to gain the attention of the farmer and get them to really implement a strategy on their farm you need to show them how it will impact their bottom line and/or improve the health of their animals or the quality of the feeds they are growing.  If it doesn’t benefit the dairy operation in some way it will never reach the top of the priority list even though it is on the list.   

eXtension - A Great Resource

eXtension is a website that was developed within the last 5 years and is turning into a great resources on a number of issues.  All the material on the website is peer reviewed and comes from reputable research institutions and extension professionals so it can be trusted.  It has information on the following general topic areas:

• Community - master gardening and entrepreneurship
• Disaster Issues - floods, oil spill, wildfires, and agrosecurity
• Energy - farm and home 
• Family - child care, food and fitness, care giving, food safety, parenting, and personal finance
• Farm - manure management, bee health, beef cattle, dairy cattle, corn and soybean production, cotton, goats,  horses, organic, and small meat processors
• Pest Management 
• Youth   

Hidden under the "manure management" sub-section of the "Farm" tab is a great page on environmental regulations related to livestock and poultry operations.  This explains both water and air quality regulations that are enforced at the national level.  There are many state and local regulations that farmers will also need to follow which aren't discussed on this page, but it is still a great resource for the national laws.  On other pages is a dearth of information on environmental tools and management strategies that can be employed on varies types of farms.

Fly Away Fly

Flies are an unwelcome guest on any farm.  Farmers get a lot of complaints from neighbors about flies, and in most cases the farmer doesn't like the flies any more than the neighbor does.  Flies are a nuisance to everyone, farmer, neighbor, and animal.  Flies can cause disease, spread disease, or bother animals enough that they lose production.  There are many options to control flies on a farm from sprays, fly paper, dusters, to parasitic wasps, but one of the most overlooked ways to reduce flies on a farm is to keep the farm as clean as possible.  Manure, feed, and milk are three of the biggest draws for flies to keeping those things cleaned up on the farm will help to reduce fly pressure.  Some things to think about would be:  make sure barnyards are cleaned regularly, stalls are cleaned and freshly bedded daily, milk houses washed after each milking, spilled milk around calf hutches is cleaned up, and spilled feed is cleaned up.  Flies are drawn to food sources and places to lay their eggs and if those options are not available on the farm they will move on.  The added benefit to keeping the farm neat and clean is that it will reduce the chances of runoff from the farm that can lead to water quality concerns, and it will give a positive impression to the neighbors that the farm is doing the right thing.  I should state that there will always be flies on a farm no matter what anyone does, but keeping them at a manageable level is the goal.

Rain!!

After almost of a month of no rain we finally got some much needed precipitation here in Lancaster County.  Unfortunately we got 3-4 inches in a span of a few days, which under traditional cropping strategies could have made for a very muddy situation not only on land, but also in the local waterways.  However, because so many farmers have adopted no-till farming practices the fields were able to absorb this water preventing the local streams from becoming that familiar muddy color.  In this area around 50% of land is in no-till production, which is a great tribute to farmer's concern for local water quality.  There are many other states that cannot boast such a high number of no-till acres.  The benefit to no-till is that there is residue from last year's crop still covering the top of the soil.  This residue inhibits the flow of water allowing more it to be absorbed into the soil instead of running off into local streams.  Excessive runoff from a field, which could have easily happened during this rain event, can carry with it nutrients and sediment that will then contaminate local waterways.  Also, because the water had a better opportunity to be absorbed into the soil the plants will benefit from this rain for weeks to come. 

Hazy, Hot, and Humid!!

Summer has officially arrived, and with it the heat and humidity. As uncomfortable as these hot days can be for us cows are even more miserable. Farmers do all they can to make the cows comfortable, but you can’t air condition the outdoors.

Dairy cows are most comfortable between 41oF and 77oF, but obviously if the humidity is high even lower temperatures can become uncomfortable. When cows get too hot and uncomfortable they eat less, which leads to less milk production. For example, increasing the temperature from 68oF to 86oF can reduce milk production by almost 10 lbs. One a 100-cow dairy that would equate to 1000 lbs less milk per day and with the current milk price of around $15 per hundred pounds that would equate to $150 in lost profit to the dairy producer each day just from the heat!

Due to the significant production losses that can be seen with heat stress in cows, farmers do lot a try to keep their cows cool. The most obvious is to provide plenty of water. Milk is 87% water so even in cooler weather cows need at least 20 to 25 gallons of water a day, but in hot weather they will drink up to 30 to 35 gallons. Of course, this water has to be provided in enough areas so cows don’t have to stand in line for water, and it should be provided in clean waterers. Cows on pasture are very susceptible to heat stress because they are more exposed to the heat so making sure they have enough water is even more crucial.

Shade is the other thing we think of as a way to cool down. Cows that are housed in barns already have shade available, but cows on pasture need a tree or some type of shade to stay cool. Many farms try to provide shade to their cows, but it is not always possible to provide shade on the pasture. Therefore, many farmers, who graze their cows, will bring them into the barn during the hottest part of the day to provide some relief from the sun and heat.
Fans are another option used on farms to keep cows cool. Almost all barns have fans in the main stall area, holding areas, and the milking parlor. Fans help move the air over the cows and evaporates the heat. There a many types of fans used on farms and one type, tunnel ventilation, you can see from the road. These farms have fans at one end of the barn and an opening at the other end, which allows the fans to pull air through the barn cooling the cows in the process. Also, there are fans in the barn itself directly over the cows that helps move the air even more.

Fans are a great way to cool cows, but adding sprinklers on top of using the fans is even better. Sprinklers are usually set on timers so that they come on every few minutes during hot weather. They are placed over the feeding areas so as not to get the bedding area wet. Sprinklers cool cows, much as running through a sprinkler cools you. When cows eat they get wet from the sprinkler and then the air movement from the fans evaporates the heat from the cow even faster than fans alone.